This invention relates to pipes having a wall surface formed from an abrasion resistant material and, more specifically, to fiberglass-reinforced resin pipes having an internal liner and/or outside surface formed from an elastomeric abrasion resistant material.
Pipes, and more specifically fiberglass-reinforced resin pipes, that are used in slurry transport or other abrasive transport service are subjected to a high degree of abrasive wear. The use of fiberglass reinforced resin pipes in such abrasive service, although desired for purposes of corrosion resistance, weight savings and expense, is not practical because such abrasive service causes the inside diameter of such pipes to wear and eventually fail, thereby providing a limited service life.
Efforts have been made to improve the abrasion resistance of fiber-reinforced resin pipes by providing an inside diameter or inner liner made from materials that are relatively more abrasion resistant than the pipe itself. For example, it is known in the art to provide an internal liner for such pipes that is made from rubber to absorb the impact of abrasive particles, thereby reducing damage to the underlying pipe wall. Additionally, U.S. Pat. No. 5,184,706 discloses a fiberglass-reinforced polyurethane pipe that includes an internal liner that is formed from polyurethane to improve the abrasion resistance of the pipe.
A disadvantage of these proposed solutions is that they are not well suited for fiberglass reinforced pipes that use epoxy resin because the rubber and polyurethane material does not form a good bond to the underlying pipe surface. The failure to form a good bond with the pipe prevents the formation of an internal liner useful for abrasion resistant service because the liner itself can be separated from the pipe wall during service, thereby, leaving the underlying pipe wall surface exposed and unprotected. Additionally, the use of rubber and polyurethane materials as an internal liner does not provide a sufficient degree of chemical, temperature, toughness, and abrasion resistance for some abrasive services.
Another technique that has been used to improve the abrasion resistance of such pipes is to improve the hardness of the pipe inside diameter by incorporating ceramic beads or similar hard particles into the resin matrix itself. However, the manufacturing time and raw materials costs associated with implementing this technique, not to mention the weight increase associated with using such beads or particles, makes this technique an unattractive solution.
It is, therefore, desired that fiberglass-reinforced resin pipe be constructed comprising an inside diameter or internal liner formed from an elastomeric material that is abrasion resistant and capable of forming a good chemical bond to the pipe wall. It is desired that the elastomeric abrasion resistant material provide improved properties of toughness and chemical, temperature, and abrasion resistance when compared to polyurethane lined pipes. It is desired that an abrasion resistant pipe comprising such internal liner be relatively easy to manufacture using existing fiberglass-reinforced resin pipe manufacturing techniques, and not add significantly to the weight of the finished abrasion resistant pipe.
Abrasion resistant pipes of this invention comprise a structural wall formed from a filament wound fiberglass-reinforced material, and an elastomeric abrasion resistant material disposed along the inside and/or outside surface of such pipe. In a preferred embodiment, the structural pipe wall is formed from a filament wound fiberglass-reinforced epoxy resin material, and the abrasion resistant material is formed from a polyurea elastomer. Preferably, the polyurea elastomer is one formed from a 2-component system comprising a first isocyanate-containing component, and a second amine-containing resin component that are combined in a 1:1 volume ratio.
Abrasion resistant pipes of this invention are manufactured using existing filament winding processes by first coating a mandrel with the elastomeric abrasion resistant material, and than winding the resin impregnated filament therearound. A strong chemical bond is formed between the elastomeric abrasion resistant material and the adjacent fiberglass-reinforced resin layer, when the abrasion resistant material is a polyurea elastomer and the fiberglass impregnating resin is an epoxy resin, and the filament winding process is initiated before the underlying polyurea elastomer is allowed to fully cure. The strong bond between the cured abrasion resistant material and the adjacent pipe structural wall surface is desired to ensure that the liner does not separate from the pipe to provide maximum protection against abrasive wear.
Pipes prepared according to principles of this invention have improved properties of toughness, temperature resistance, chemical resistance, and abrasion resistance when compared to conventional fiberglass-reinforced pipes that either have no protective liner or have liners formed from other elastomeric materials.